Method of dynamic thermal management of electronic device

ABSTRACT

To dynamically manage a temperature of an electronic device, a local temperature is provided by measuring a temperature of a local spot in the electronic device and a reference temperature is provided by measuring a temperature of a reference spot in the electronic device where the reference spot and the local spot are thermally coupled. A target temperature corresponding to a limit value of the reference temperature is adjusted based on the local temperature and a power level of the electronic device is controlled based on the same target temperature. The target temperature may be set to a relatively high value to secure performance of the electronic device when the local temperature is relatively low. Alternatively, the target temperature may be set to a relatively low value to pursue stability of the electronic device when the local temperature is relatively high.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation application of U.S. patentapplication Ser. No. 15/841,734, filed on Dec. 14, 2017, which claimsunder 35 U.S.C. § 119 priority and the benefit of Korean PatentApplication No. 10-2017-0029747, filed on Mar. 8, 2017, in the KoreanIntellectual Property Office, the entire contents of which are herebyincorporated by reference.

BACKGROUND 1. Technical Field

Example embodiments relate generally to an electronic device, and, moreparticularly, to a method of dynamic thermal management of an electronicdevice.

2. Discussion of the Related Art

Modern electronic devices commonly include integrated circuits such assystem-on-chip (SOC) circuits. The SOC commonly takes the form of achip, and, in particular, a microelectronics system integrated onto thechip. In recent years, various circuits having synergistic functionalityare integrated together on the same chip in an effort to increase thedegree of integration of the SOC. In addition, the operational speed ofthe SOC continues to increase in order to satisfy user demand. As thedegree of integration and the operational speed of SOCs continue toincrease, temperature management, or thermal management, becomes anincreasingly important factor in the monitoring and controlling oftemperature variation of the SOC.

SUMMARY

Some example embodiments provide a method of dynamic thermal managementfor efficiently controlling a temperature of an electronic device, whilemaintaining stable operation.

Some example embodiments provide an electronic device that performs amethod of dynamic thermal management for efficiently controlling atemperature of the electronic device, while maintaining stableoperation.

According to example embodiments, a method of dynamic thermal managementof an electronic device comprises: providing a local temperaturemeasurement by measuring a local temperature of a local spot in theelectronic device; providing a reference temperature measurement bymeasuring a reference temperature of a reference spot in the electronicdevice, the reference spot being thermally coupled to the local spot;adjusting a target temperature corresponding to a limit value of thereference temperature measurement based on the local temperaturemeasurement; and controlling a power output of the electronic devicebased on the target temperature.

According to example embodiments, a method of dynamic thermal managementof a portable electronic device comprises: providing a local temperaturemeasurement by measuring a temperature of a hot spot adjacent to a heatsource of the portable electronic device; providing a referencetemperature measurement by measuring a temperature of a housing case ofthe portable electronic device, the housing case being thermally coupledto the hot spot; adjusting a target temperature corresponding to a limitvalue of the reference temperature measurement when the localtemperature measurement increases; and controlling a power level of theportable electronic device based on the target temperature.

According to example embodiments, a temperature management circuit of anelectronic device comprises: a local temperature sensor configured toprovide a local temperature measurement by measuring a temperature of alocal spot in the electronic device; a reference temperature sensorconfigured to provide a reference temperature measurement by measuring atemperature of a reference spot in the electronic device, the referencespot being thermally coupled to the local spot; and a temperaturemanagement unit configured to change a target temperature correspondingto a limit value of the reference temperature measurement based on thelocal temperature measurement.

The method of dynamic thermal management of the electronic deviceaccording to example embodiments may efficiently perform thermalmanagement of the electronic device by changing the target temperaturecorresponding to a limit value of the reference temperature based on thelocal temperature. In some embodiments, the local spot and the referencespot are thermally coupled. The target temperature may be set to arelatively high value to secure performance of the electronic devicewhen the local temperature is relatively low. Alternatively, the targettemperature may be set to a relatively low value to pursue stability ofthe electronic device when the local temperature is relatively high.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects and features of the present disclosure willbecome apparent by describing in detail example embodiments thereof,with reference to the attached drawings, in which:

FIG. 1 is a flow diagram representing a method of dynamic thermalmanagement of an electronic device according to some embodiments of thepresent disclosure.

FIG. 2 is a diagram representing a layout of a temperature managementcircuit in an electronic device according to some embodiments of thepresent disclosure.

FIG. 3 is a block diagram representing an electronic device including atemperature management circuit according to some embodiments of thepresent disclosure.

FIG. 4 is a block diagram representing an example embodiment of atemperature management unit included in the electronic device of FIG. 3.

FIG. 5 is a graph representing a method of determining a targettemperature according to some embodiments of the present disclosure.

FIG. 6 is a graph representing a method of thermal management of anelectronic device in a situation in which a target temperature is fixed.

FIG. 7 is a graph representing a method of thermal management of anelectronic device when a target temperature is changed in someembodiments of the present disclosure.

FIGS. 8, 9 and 10 are diagrams representing methods of thermalmanagement of an electronic device when a target temperature is changedaccording to some embodiments of the present disclosure.

FIG. 11 is a conceptual diagram representing an electronic deviceaccording to some embodiments of the present disclosure.

FIG. 12 is a block diagram representing some embodiments of a localtemperature sensor included in the electronic device of FIG. 11.

FIG. 13 is a circuit diagram representing some embodiments of atemperature detector included in the local temperature sensor of FIG.12.

FIG. 14 is a diagram representing some embodiments of a referencetemperature sensor included in the electronic device of FIG. 11.

FIG. 15 is a diagram representing a method of temperature managementaccording to some embodiments of the present disclosure.

FIG. 16 is a diagram representing a layout of a temperature managementcircuit in an electronic device according to some embodiments of thepresent disclosure.

FIG. 17 is a diagram representing a mobile device according to someembodiments of the present disclosure.

DETAILED DESCRIPTION OF EMBODIMENTS

Various example embodiments are described more fully herein withreference to the accompanying drawings, in which some exampleembodiments are shown. In the drawings, like numerals refer to likeelements throughout.

FIG. 1 is a flow diagram representing a method of dynamic thermalmanagement of an electronic device according to some embodiments of thepresent disclosure.

Referring to FIG. 1, a local temperature may be provided by measuring atemperature of a local spot in an electronic device (S100). A referencetemperature may be provided by measuring a temperature of a referencespot in the electronic device (S200), where the reference spot isthermally coupled to the local spot. The term “thermally coupled”, asused herein, may represent that there is present a heat conduction pathof a certain thermal conductivity between the local spot and thereference spot and may represent that a temperature change of one spotaffects a temperature of the other corresponding spot. The local spotand the reference spot may be properly determined depending on theoperation scenario of the given electronic device. The local temperatureand the reference temperature may be provided, for example, usingtemperature sensors of various types known to those of ordinary skill inthe art. Example embodiments of the local and reference spots and thetemperature sensors are described herein in connection with theembodiments of FIGS. 11 through 14. The term “spot” as used herein canrefer to a particular location or region of the electronic device, itschip, its package, or another portion of the device where temperaturemonitoring is desired.

In some embodiments, a target temperature corresponds to a limit valueof the reference temperature. In some embodiments, the targettemperature may be changed or adjusted based on the local temperature(S300). In some embodiments, a power level of the electronic device maybe controlled in response to the target temperature (S400).

Electronic devices continue to become more highly integrated. At thesame time, consumers continue to demand increased performance.Accordingly, semiconductor packages also likewise manufactured to have arelatively small size and high density. The relatively higherperformance of high-density semiconductor packages operating at higherspeeds results in the generation of increased heat present in thesemiconductor packages. Thus, sufficient thermal dissipation becomes oneof the most important factors for increasing operation stability andproduct reliability of semiconductor packages and electronic systemsincluding the semiconductor packages. The term “sufficient” in thisscenario, in connection with thermal dissipation, allows and accountsfor certain limits to be put in place to prevent overheating and tomaintain the operational temperature within a proper range.

In some electronic devices, such as mobile electronic devices, thetemperature of a semiconductor chip and the temperature of a surface ofa housing case may be increased due to the heat generated throughoperation of the electronic device. Such an increase in the temperatureof the semiconductor chip may cause malfunction, reliabilitydegradation, lifetime reduction, or other concerns. An increase in thetemperature at the housing surface, or at locations external to device,can, in some cases, burn the skin of a user, or otherwise causedispleasure to a user. In view of these concerns, in the optimizationand operation of an electronic device including an integrated circuit ora semiconductor chip, a dynamic thermal management (DTM) process may beadopted. In some example embodiments, a DTM process may be employed sothat the operation of the semiconductor chip in the electronic devicemay be automatically halted by temperature control software in a casewhere an operational temperature of the semiconductor chip is increasedover a predetermined target temperature.

For example, according to the DTM process of the present embodiment, atarget temperature of the semiconductor chip and/or a target temperatureof the housing case may be set in advance of the operation. Operation atof the semiconductor chip in some embodiments may be restrictedautomatically if the operational temperature of the semiconductor chipexceeds the predetermined target temperature and/or if the operationaltemperature of the housing case exceeds the predetermined targettemperature.

In some embodiments, a spot of the most significant heat source may beselected as a desired location for monitoring temperature in connectionwith the DTM process. At the same time, the actual spot of the maximumtemperature of an electronic device may be varied depending on theoperational scenario of the device. While this approach might allow foroperational determinations based on the most volatile or extremetemperature spot in a DTM operation, under this scenario, thetemperature of the semiconductor chip may be allowed to increaseexcessively if the DTM process is based on a temperature of only asingle spot. In addition, if the target temperature is fixed to aconstant value, then the process is not suitable for detecting abruptchanges in operational conditions.

The method of dynamic thermal management of the electronic deviceaccording to some embodiments may efficiently perform thermal managementof the electronic device by changing the target temperaturecorresponding to a limit value of the reference temperature based on thelocal temperature in a configuration when the local spot and thereference spot are thermally coupled. The target temperature may be setto a relatively high value to secure performance of the electronicdevice when the local temperature is relatively low. The targettemperature may be set to a relatively low value to pursue stability ofthe electronic device when the local temperature is relatively high.

FIG. 2 is a block diagram of a layout of a temperature managementcircuit in an electronic device according to some embodiments of thepresent disclosure.

Referring to FIG. 2, a temperature management circuit in an electronicdevice 1000 may include a temperature management unit or a thermalmanagement unit (TMU) 100, a reference temperature sensor (SNR) 200 andat least one local temperature sensor (SNL) 300. Throughout thespecification, the acronym TMU refers to either the temperaturemanagement unit or a thermal management unit 100. FIG. 2 represents asystem including one, single, local temperature sensor 300 for theconvenience of description; however, the number of local temperaturesensors 300 may vary according to a configuration of the electronicdevice 1000. Other elements in the electronic device 1000 are omitted inthis embodiment, except for those corresponding to the operation of thetemperature management unit 100.

In some embodiments, the electronic device 1000 may include a system onchip (SOC) and the SOC may include a single or a plurality of subsidiaryblocks (BLKi) wherein “i”=1,2,3,4, etc. which may be individualized bytheir own individual functions. For example, the subsidiary blocks BLKimay include a core block which may include a central processing unit, amemory controller, a display controller block, a file system block, agraphic processing unit block, an image signal processing block, amulti-format codec block, and or any other component known to those ofordinary skill in the art. These subsidiary blocks may correspond tosignificant heat sources that are present in the SOC. In someembodiments, it may be desired to monitor and control the respectivetemperatures of the subsidiary blocks BLKi in addition to the overalltemperature of the SOC.

In some embodiments, the reference temperature sensor 200 may monitorand measure a temperature of a reference spot (RS) in order to provide areference temperature (TR). The local temperature sensor 300 may measurea temperature of a local spot (LS) in order to provide a localtemperature (TL). The reference spot RS and the local spot LS may bespaced apart from each other on the electronic device 1000, and may bethermally coupled through a medium comprising a certain thermalconductivity.

The temperature management unit 100 may provide a target temperature(TRT) and temperature information (DTI) based on the measured localtemperature (TL) and the measured reference temperature (TR). Accordingto some embodiments, the temperature management unit 100 may change thetarget temperature (TRT) as a result of a limit value of the referencetemperature TR relative to the local temperature TL. The power level ofthe electronic device 1000 may be controlled based on the temperatureinformation DTI and the target temperature TRT received from thetemperature management unit 100.

In some embodiments, the local spot LS may be selected to correspond toa hot spot in the region of, or adjacent to, a heat source or a heataggressor in the electronic device 1000. In other embodiments, the localspot LS may correspond to an arbitrary spot that is affected by thetemperature of the local spot LS. In other words, in some operationalsituations, the reference temperature TR of the reference spot RS may beequal to or lower than the local temperature TL of the local spot LS.This may be beneficial for determining the heat difference correspondingto thermal coupling between the reference spot RS and the local spot LS.

In an example embodiment, the local spot LS may be positioned in theregion of a processor that generates a large amount of heat and thereference spot RS may be positioned on a housing case of the electronicdevice 1000. Such close proximity between the local spot LS andreference spot RS may be preferred for determining information relatedto the differences in temperature in a local area. In this embodiment,as will be described below with reference to FIGS. 11 through 14, thereference temperature sensor SNR 200 may be implemented as a non-contacttemperature sensor and the local temperature sensor SNL 300 may beimplemented as an on-chip temperature sensor that is integrated into theprocessor or may be otherwise present on the semiconductor die, in whichprocessor is integrated, for example, according to techniques known tothose of skill in the art.

FIG. 3 is a block diagram representing an electronic device including atemperature management circuit according to some embodiments of thepresent disclosure.

Referring to FIG. 3, an electronic device 1000 may include a temperaturemanagement unit (TMU) 100, a reference temperature sensor (SNR) 200, atleast one local temperature sensor (SNL) 300, a processor 400, a powermanagement unit (PMU) 500, a voltage control unit (VCU) 600 and a clockcontrol unit (CCU) 700. The embodiment of FIG. 3 represents aconfiguration that employs a single local temperature sensor SNL 300 forthe convenience of description, but the number of the subsidiary localtemperature sensors may vary according to the desired configuration ofthe electronic device 1000. The electronic device 1000 may compriseother various components which are omitted in FIG. 3 for the convenienceof description of the inventive concepts.

As described herein, the reference temperature sensor SNR 200 maymeasure a temperature of a reference spot RS to provide a referencetemperature TR. The local temperature sensor SNL 300 may measure atemperature of a local spot LS to provide a local temperature TL. Insome embodiments, the reference spot RS and the local spot LS may bespaced apart and may be thermally coupled through a medium having acertain thermal conductivity.

In some embodiments, the temperature management unit 100 may provide atarget temperature TRT and temperature information DTI based on thelocal temperature TL and the reference temperature TR. According to someembodiments, the temperature management unit 100 may change the targettemperature TRT corresponding to a limit value of the referencetemperature TR based on the local temperature TL. In some embodiments,the temperature management unit 100 may be initialized and controlled bya temperature management control signal TCTR from the processor 400. Insome embodiments, the temperature management unit 100 may generate atripping signal TRP when the local temperature TL and/or the referencetemperature TR satisfy certain conditions. For example, the temperaturemanagement unit 100 may generate the tripping signal TRP when thereference temperature TR increases excessively over the targettemperature TRT. The power management unit 500 may block a power of someor all circuit blocks in the electronic device 1000 in response to thetripping signal TRP.

A tripping signal is known to those of ordinary skill in the art as anopen circuit that prevents the flow of current when certain signals arepresent. In some embodiments related to the present disclosure, if thelocal temperature is significantly higher than the reference temperaturea trip signal can be generated to deactivate certain circuits of theelectronic device in order to prevent overheating.

The processor 400 may generate the temperature management control signalTCTR and the power management control signal PCTR for controllingoperations of the electronic device 1000 based on the target temperatureTRT along with the temperature information DTI. In some embodiments, thetemperature information DTI may include information related to thereference temperature TR and the local temperature TL. In someembodiments, the processor 400 may manage the presentation of power ofthe electronic device 1000 through a dynamic voltage and frequencyscaling (DVFS) process using a DVFS module 410, as represented withinthe processor.

The DVFS process in some configurations, operates to vary a voltageand/or a frequency of operation of the electronic device, or of certainunits of the electronic device, depending on the operational conditionsof a processor 400. In some embodiments, the DVFS module 410 may includesoftware that is executed by the processor 400. In other embodiments,the DVFS module 410 may be executed as hardware and/or firmware.

The DVFS module 410 generally may determine an operational power levelamong a plurality of different power levels corresponding to a presentoperational condition. In some embodiments, the power level or the poweroutput may be represented by at least one of the operational voltage andthe operational frequency. In other words, the power level or the poweroutput may be adjusted by changing at least one of the operationalvoltage and the operational frequency. In some embodiments, theoperational voltage may be a power supply voltage and the operationalfrequency may be a frequency of an operational clock signal.

The DVFS module 410 may monitor the operational status or theoperational condition such as workload, an operating temperature, or anyoperation known to one of ordinary skill in the art, of the processor400 to determine the operating power level which corresponds to thepresent operational condition. For example, when the workload of theprocessor 400 increases, the DVFS module 410 may raise the operatingpower level to increase the operational voltage and/or the operationalfrequency. Conversely, when the workload of the processor 400 decreases,the DVFS module 410 may lower the operating power level to decrease theoperational voltage and/or the operational frequency. When theoperational temperature increases to a temperature that is out of anormal operation range, the DVFS module 410 may lower the operatingpower level to decrease the operational voltage and/or the operationalfrequency. As a result, the power level of the electronic device 1000may be appropriately controlled to achieve operation within a safetemperature range for securing and maintaining a stable operation of theelectronic device 1000. Control in this manner serves to optimize theperformance of the electronic device 1000, and in part to protect thedevice itself and to protect the user.

In some embodiments, the power management unit 500 may control thevoltage control unit 600, also referred to as VCU and the clock controlunit 700, also referred to as CCU. They can be controlled based on thepower management control signal PCTR received from the processor 400such that at least one of the operational frequency and the power supplyvoltage may be adjusted. In some embodiments, as illustrated in FIG. 3,the power management unit 500 may generate a voltage control signal VCTRand a clock control signal CCTR, as shown, to control operation of thevoltage control unit 600 and operation of the clock control unit 700.While the present example embodiments illustrates the voltage controlunit 600 and/or the clock control unit 700 as units or blocks externalto, or independent of, the power management unit 500, other embodimentsare possible. For example, in other example embodiments, the powermanagement unit 500 may include the voltage control unit 600 and/or theclock control unit 700 integral with the power management unit 500.

The voltage control unit 600 may provide power supply voltages VOP1 andVOP2 to the subsidiary blocks BLKi illustrated in and described in FIG.2 above. In some embodiments the voltage control unit 600 may include atleast one voltage regulator. The voltage control unit 600 may bereferred to generally as a power supply or a power management integratedcircuit (PMIC). According to embodiments, the voltage control unit 600may be implemented as another chip distinct from a chip in which theprocessor 400 is integrated, or, optionally, at least a portion of thevoltage control unit 600 may be included in the chip of the processor400. The voltage control unit 600 is not limited to generation of twopower supply voltages VOP1, VOP2. For example, the voltage control unit600 may generate a single power supply voltage or multiple power supplyvoltages of a number higher than two.

The clock control unit 700 may generate operational clock signals OCK1and OCK2 that are provided to the subsidiary blocks BLKi. The clockcontrol unit 700 may include at least one of a phase-locked loop (PLL),a delay-locked loop (DLL), a clock multiplier, and a clock diver. Theclock control unit 700 is not limited to generation of two operationalclock signals OCK1, OCK2. For example, the clock control unit 700 maygenerate a single operational clock signal or multiple operational clocksignals of a number higher than two.

The power management unit 500 may generate a voltage control signal VCTRand a clock control signal CCTR so that the voltage control unit 600 andthe clock control unit 700 may provide an appropriate operationalvoltage and operational frequency corresponding to the desired operatingpower level. The change of the power level may include change of atleast one of the operational voltage and the operational frequency. Insome scenarios the operational voltage may be adjusted. In somescenarios the operational frequency may be adjusted. In some scenariosthe operational voltage and operational frequency may both be adjusted.

The power management unit 500 may control the power level of a portionof the electronic device 1000 independently of the power level ofanother portion of the electronic device 1000. For example, when thesubsidiary blocks BLK1˜BLK4 in FIG. 2 are included in different powerdomains, the operating voltages VOP1 and VOP2 provided to the subsidiaryblocks BLK1˜BLK4 may be controlled independently to enhance theperformance of the device. Additionally, when the subsidiary blocksBLK1˜BLK4 are included in different clock domains, the operating clocksignals OCK1 and OCK2 provided to the subsidiary blocks BLK1˜BLK4 may becontrolled independently.

FIG. 4 is a block diagram representing an example embodiment of atemperature management unit included in the electronic device of FIG. 3.

Referring to FIG. 4, a temperature management unit 100 may include asensor controller 120, a register unit 140, a temperature sampler 160and a target temperature generator 180.

The temperature sampler 160 may sample certain locations and provide thereference temperature TR from the reference temperature sensor 200 andthe local temperature TL from the local temperature sensor 300. Thetemperature sampler 160 may sample the reference temperature TR and thelocal temperature TL in any time frame in response to a timing signalfrom the sensor controller 120. In various embodiments, the sampling ofthe temperature sampler 160 may occur in periodic fashion or innon-periodic fashion.

The register unit 140 may store the temperature information DTI, such asthe target temperature TRT and other operational information based onthe target temperature management control signal TCRT from the processor400 in FIG. 3. The temperature information DTI may include the activereference temperature TR and the active local temperature TL. Inaddition, the resister unit 140 may generate interrupt signals such as atripping signal TRP, as described above. The operational informationstored in the register unit 140 may include an enable status value, aninterrupt status value, a sensing period value of the temperaturemanagement unit 100, or any other value known to one of ordinary skillin the art suitable for operation of the temperature management unit100.

The target temperature generator 180 may generate the target temperatureTRT corresponding to the limit value of the reference temperature TRbased on the local temperature TL. The target temperature generator 180may change the target temperature TRT according to the change of thelocal temperature TL as stored in and received from the register unit140. Temperature management of the electronic device 1000 may thereby beperformed efficiently by controlling the power level of the electronicdevice 1000 based on the target temperature TRT changing accordingly.

FIG. 5 is a graph representing a method of determining a targettemperature according to some embodiments of the present disclosure.

FIG. 5 represents a first case TRT1 in which the target temperature TRTis maintained at a constant value regardless of the local temperature TLand a second case TRT2 in which the target temperature TRT is decreasedwhen the local temperature TL is increased according to exampleembodiments. The second case is displayed as a negatively sloped line.The target temperature generator 180 in FIG. 4 may decrease the targettemperature TRT when the local temperature TL measured by the localtemperature sensor SNL increases. In some embodiments this decrease intarget temperature is illustrated as having a linear relationship; inother cases, this can take a higher-order, non-linear relationship.

In some embodiments, the target temperature TRT may be decreased with aconstant slope as the local temperature TL increases as illustrated inFIG. 5. The operation of changing the target temperature TRT relative tothe local temperature LT is not limited to that of FIG. 5 and may beimplemented according to various other forms as illustrated in FIGS. 8through 10. As represented in FIGS. 8 through 10, target temperature maybe set to a relatively high value to secure and validate performance ofthe electronic device when the local temperature is relatively low andthe target temperature may be set to a relatively low value to pursuestability of the electronic device when the local temperature isrelatively high.

FIG. 6 is a graph representing a method of thermal management of anelectronic device when a target temperature is fixed, and FIG. 7 is agraph representing a method of thermal management of an electronicdevice when a target temperature is changed according to an exampleembodiment.

FIG. 6 illustrates the local temperature TL and the referencetemperature TR when the target temperature TRT is maintained constant asrepresented in the first case TRT1 in FIG. 5. In FIG. 6, a firstreference temperature TR1 and a first local temperature TL1 correspondto a case when the target temperature TRT is fixed to approximately 83°C. (181.4° F.) and a second reference temperature TR2 and a second localtemperature TL2 correspond to a case when the target temperature TRT isfixed to approximately 77° C. (170.6° F.).

In general, a spot of the most significant or active heat source may beselected as the local spot LS to monitor a temperature of the local spotLS for the DTM operation. The spot of the most significant heat source,that is, the spot of the maximum temperature may be varied depending onthe operational scenario of the electronic device and thus the localtemperature TL of the local spot LS corresponding to the hot spot may beincreased excessively.

As illustrated in FIG. 6, if the target temperature is fixed to about83° C., overshooting of the temperature may be caused due to increase ofthe power level according to the DVFS operation and thus the first localtemperature TL1 may be increased abruptly to about 125° C. (257° F.).The abrupt temperature increases may result in malfunction of a circuitin the vicinity of the local spot LS and could potentially causeirreversible damage to the circuit.

To address and overcome such problems, the target temperature TRT may belowered to 77° C. so that the second local temperature TL2 may be keptbelow 120° C. (248° F.). However, if the target temperature TRT islowered, the power level according to the DVFS operation may be limitedexcessively and thus the performance of the electronic device may bedegraded, which is an inconvenience to the user. In other words, if thetarget temperature TRT is fixed to a lower value without considerationof the present operational conditions, the operational voltage and/orthe operational frequency may be lowered unnecessarily. As a result theunnecessary lowered power level may cause degradation of the performanceof the electronic device.

FIG. 7 represents the local temperature TL and the reference temperatureTR when the target temperature TRT is changed based on the localtemperature TL as the second case TRT2 in FIG. 5. In FIG. 7, a thirdreference temperature TR3 and a third local temperature TL3 correspondto a case when the target temperature TRT is decreased as the localtemperature TL increases.

Overshooting of the third local temperature TL3 may be suppressed asrepresented in FIG. 7 if the target temperature TRT is decreased as thelocal temperature TL increases. The performance of the electronic devicemay be degraded unnecessarily because the target temperature TRT is notfixed to a relatively low level. This may result in degradedperformance.

The high-temperature region REG indicated by a circuit in FIG. 7 by adashed circle, is a relatively small interval of the entire operationtime. Overshooting of the local temperature TL may be prevented bysufficiently decreasing the target temperature TRT during the relativelyshort time interval corresponding to the high-temperature region REG andthe performance of the electronic device may be enhanced by increasingthe target temperature TRT during the long time interval of operationbeyond the high-temperature region REG.

As such, the method of dynamic thermal management of the electronicdevice according to some embodiments may efficiently perform thermalmanagement of the electronic device by changing the target temperaturecorresponding to a limit value determined by the reference temperaturebased on the local temperature when the local spot and the referencespot are thermally coupled. The target temperature may be set to arelatively high value to secure performance of the electronic devicewhen the local temperature is relatively low. Furthermore, the targettemperature may be set to a relatively low value to pursue stability ofthe electronic device when the local temperature is relatively high, incomparison.

FIGS. 8, 9 and 10 are diagrams representing various methods of thermalmanagement of an electronic device when a target temperature is changedaccording to example embodiments. In FIGS. 8, 9 and 10, the horizontalaxis indicates the local temperature TL of the local spot LS and thevertical axis represent the target temperature TRT corresponding to alimit value of the reference temperature TR.

Referring to FIGS. 8 and 9, the target temperature TRT may change bysetting a boundary value T0 of the local temperature TL and controllingthe change of the target temperature TRT based on the local temperatureTL and the boundary value T0 and the relationship of the boundary valueand the local temperature.

In some embodiments, as represented in FIG. 8, the target temperaturegenerator 180 in FIG. 4 may maintain the target temperature TRT to beconstant regardless of the local temperature TL when the localtemperature TL is lower than the boundary value T0 and may decrease thetarget temperature TRT as the local temperature TL increases when thelocal temperature TL is higher than the boundary value T0. In someembodiments, the boundary value T0 can be viewed as a thresholdtemperature. At values greater than the threshold temperature T0,greater control of the operating temperature is desired in order tomanage the target temperature.

In other example embodiments, as represented in FIG. 9, the targettemperature generator 180 may decrease the target temperature TRTaccording to a first negative slope as the local temperature TLincreases when the local temperature TL is lower than the boundary valueT0 and may decrease the target temperature TRT with a second negativeslope of greater magnitude than the first negative slope as the localtemperature TL increases to a level higher than the boundary value T0.Referring to FIG. 9, the first slope corresponds to |tan(θ1)| and thesecond slope corresponds to |tan(θ2)|.

Even though the example embodiments of FIGS. 8 and 9 illustrate a singleboundary value T0, those skilled in the art may understood that aplurality of boundary values may be set at different ranges on the graphand methods of changing the target temperature TRT may be determinedwith respect to each range of the local temperature TL.

In some example embodiments, the values T0, 01 and 02 may be providedthrough the control signal TCTR and stored in the register unit 140 inFIG. 4 during an initializing process of the electronic device. Thevalues T0, 01 and 02 may be determined properly in a designing processor a testing process of the electronic device depending on theoperational scenario of the electronic device. These values can be usedto determine the rate at which the target temperature changes.

Referring to FIG. 10, in another embodiment, the target temperature TRTmay be changed by setting a plurality of temperature sections labeled asTSECi where i=1, 2, 3, 4, etc. . . . such as TSEC1˜TSEC4 of the localtemperature TL and determining sectional values TYi where i=1, 2, 3,etc. . . . TY1˜TY4 of the target temperature TRT with respect to theplurality of temperature sections TSEC1˜TSEC4, respectively. FIG. 10illustrates the four temperature sections of the local temperature TLfor convenience of illustration and description, the number of thetemperature sections may be determined variously. For example, fewerthan four sections or more than four sections may be employed.

As illustrated in FIG. 10, the sectional values TY1˜TY4 of the targettemperature TRT may be decreased sequentially, that is, step by step, asthe local temperature TL increases.

In some example embodiments, all widths of the temperature sectionsTSEC1˜TSEC4, defined in units of temperature, may be set to be equal. Inother example embodiments, the lengths of at least two temperaturesections among the temperature sections TSEC1˜TSEC4 may be set to bedifferent or may have uneven steps in each direction.

In some example embodiments, all intervals dTY1˜dTY3 between thesectional values TY1˜TY4, defined in units of temperature, may be set tobe equal. In other example embodiments, at least two intervals among theintervals dTY1˜dTY3 may be set to be different.

The boundary values TX1˜TX5 for setting the temperature sectionsTSEC1˜TSEC4 and the sectional values TY1˜TY4 may be determined properlyin a designing process or a testing process of the electronic devicedepending on the operational scenario of the electronic device.

In other embodiments, the section values may be linear or constantbetween steps in the temperatures.

As such, the method of dynamic thermal management of the electronicdevice according to example embodiments may efficiently perform thermalmanagement of the electronic device by changing the target temperaturecorresponding to a limit value of the reference temperature based on thelocal temperature when the local spot and the reference spot arethermally coupled. In some embodiments, the target temperature may beset to a relatively high value to secure performance of the electronicdevice when the local temperature is relatively low. In otherembodiments, target temperature may be set to a relatively low value tosecure stability of the electronic device when the local temperature isrelatively high.

Hereinafter, with reference to FIGS. 11 through 14, example embodimentsare described with respect to an embodiment where the local spot LScorresponds to a hot spot of a semiconductor chip included in a portableelectronic device and the reference spot RS corresponds to a spot on ahousing case of the portable electronic device.

FIG. 11 is a conceptual diagram representing an electronic deviceaccording to example embodiments.

Referring to FIG. 11, an electronic device 1010 may be a portable ormobile electronic device that comprises a housing case 1020 and asemiconductor package 1030 mounted in the housing case 1020. Thesemiconductor package 1030 may include a package board or circuit board10 comprising an electrical circuit pattern 12 therein, a semiconductorchip 20 mounted on the package board 10 and electrically connected tothe circuit pattern 12 of the package board 10, a reference temperaturesensor 30 to detect a reference temperature TR (as described herein) ofa reference spot RS on the housing case 1020, a local temperature sensor60 to detect a local temperature TL (as described herein) of a localspot LS (as described herein) on the semiconductor chip 20 and atemperature management unit 40 to control operations of thesemiconductor chip 20 based on the local temperature TL and thereference temperature TR.

The package board 10 may comprise a plate having a sufficient rigidityand may include the circuit pattern 12 at an upper face and a lowerface. For example, the package board 10 may comprise a body 11 shapedinto a sufficiently rigid plate. The body 11 may include insulating andheat-resistive materials which may help to maintain or manage thetemperature of the interior or exterior of the electronic device. Thecircuit pattern 12 may be arranged inside the body 11. The circuitpattern 12 may include a plurality of conductive lines and may beconnected to a plurality of contact pads (not shown) arranged on thefront and the lower faces of the body 11. Contact terminals 13 may bearranged on the contact pads, at a bottom of the package board 10 and anexternal contact element (not shown) may make contact with the contactterminals 13. The semiconductor chip 20 may make contact with thecontact pads on the upper face of the body 11 and, thus, thesemiconductor chip 20 and the external contact element may beelectrically connected to each other through the circuit pattern 12 andthe contact terminals 13. For example, the contact terminals 13 mayinclude a solder ball, also known a solder bumps, as known to those ofordinary skill in the art.

In some embodiments the body 11 may comprise a thermosetting plasticplate such as an epoxy resin plate and/or a polyimide plate or any otherthermosetting plastic plate known to those of ordinary skill in the art.In another embodiment, the body 11 may include a plate on which aheat-resistive organic film, such as, a liquid crystal polyester filmand/or a polyamide film or any other heat-resistive organic film knownto those of ordinary skill in the art, may be coated. The circuitpattern 12 may include a plurality of conductive lines or wirings thatmay be electrically connected with the semiconductor chip 20 and theexternal contact elements. The circuit pattern 12 may include a powerline for applying an electric power, a plurality of signal lines forcommunicating data signals with the semiconductor chip 20 and a groundline for electrically grounding the signal lines and the power line. Theconductive lines or the wirings of the circuit pattern 12 may beelectrically insulated from one another by, for example, a plurality ofinsulation interlayers (not shown). The package board 10 may include aprinted circuit board (PCB) in which the circuit pattern 12 may beformed by, for example, a printing process.

The semiconductor chip 20 may include an active device such as anintegrated circuit device mounted on the package board 10. Therefore,when the driving power is applied to the semiconductor chip 20, anelectrical operation such as an electrical amplification and anelectrical oscillation may be conducted and, as a result, driving heatmay be generated from the semiconductor chip 20. For example, thesemiconductor chip 20 may include a plurality of conductive structures(not illustrated) stacked on a semiconductor substrate such as a siliconwafer or any other suitable substrate known to those of ordinary skillin the art. The conductive structure may be stacked on the semiconductorsubstrate using a plurality of insulation interlayers and a plurality ofwiring structures separated from the conductive structures by theindividual insulation interlayers. The wiring structure may transfersignals to the conductive structures. The conductive structures and thewiring structures may be protected from their surroundings by apassivation layer (not shown).

The semiconductor chip 20 may include a flip chip, also known ascontrolled collapse chip, structure in which an active face of thesemiconductor chip 20 may face down toward an upper surface of thepackage board 10 and, thus, interconnectors 21 such as solder bumps maybe interposed between electrode pads (not shown) of the semiconductorchip 20 and the contact pads of the package board 10. Therefore, thesemiconductor chip 20 may be electrically connected to the circuit board10 via the various interconnectors 21. The interconnectors 21 may bebonded to the circuit board 10 by a heat treatment for example, a reflowprocess and the gap space between the semiconductor chip 20 and theupper surface of the package board 10 may be filled up with anunder-filling layer (not shown). Thus, the semiconductor chip 20 may beelectrically and mechanically bonded to the circuit board 10 with highand increased reliability due to the interconnectors 21 and theunder-filling layer. An encapsulant 50 may be arranged on the packageboard 10 sufficiently covering the semiconductor chip 20. Thesemiconductor chip 20 may be sufficiently encapsulated from its externalsurroundings and may be stably fixed to the package board 10. In someembodiments, the encapsulant 50 may include a molding unit (not shown)comprising an insulating resin arranged on a whole surface of thepackage board 10 covering the semiconductor chip 20, and anunder-filling layer (not shown) interposed between the package board 10and the semiconductor chip 20. This may allow for securing of thesemiconductor chip 20 to the package board 10.

Although not shown in FIG. 11, the semiconductor chip 20 may also bemounted on the circuit board 10 in a configuration where the active facemay face upward and thus the semiconductor chip 20 may be bonded to thepackage board 10 utilizing a bonding wire. The semiconductor chip 20 mayinclude a single or a multi-chip structure such as a chip stack packagein which a plurality of the chips may be stacked. Particularly, thechips of the multi-chip structure may be electrically connected witheach other by various connecting member such as, for example,penetration electrodes, bonding wires, or other suitable connectingmembers known to those of ordinary skill in the art.

In some embodiments, the reference temperature sensor 30 detects thereference temperature TR of the reference spot RS may be a non-contacttemperature sensor. The non-contact temperature sensor 30 may bepositioned inside of the semiconductor package 1030 and may detect atemperature of the reference spot RS that is spaced apart from thenon-contact temperature sensor 30. In some embodiments, the non-contacttemperature sensor 30 may include an infrared temperature sensor whichmay detect a surface temperature of the housing case 1020 by using aninfrared radiation or multiple infrared radiation sources emitted fromthe reference spot RS.

The semiconductor package 1030 may include the local temperature sensor60 to detect the local temperature of the semiconductor chip 20. Thetemperature of the semiconductor package 1030 is determined primarily bythe heat generated by the semiconductor chip 20. Accordingly the localtemperature sensor 60 may be in communication with the semiconductorchip 20 to detect the local temperature TL at the local spot LS. Forexample, the local temperature sensor 60 may be implemented as anon-chip temperature sensor as described herein with reference to FIGS.12 and 13.

As described above, the temperature management unit 40 may generate thetemperature information DTI and the target temperature TRT correspondingto a limit value of the reference temperature TR based on the couplingbetween the local temperature TL and the reference temperature TR.According to some embodiments, the temperature management unit 40 mayadjust the target temperature TRT based on the local temperature TL.

FIG. 12 is a block diagram representing an example embodiment of a localtemperature sensor included with the electronic device of FIG. 11, andFIG. 13 is a circuit diagram illustrating an example embodiment of atemperature detector included in the local temperature sensor of FIG.12.

Referring to FIG. 12, a local temperature sensor 60 may include atemperature detector (DET) 62 and an analog-to-digital convertor (ADC)64. The temperature detector 62 may output at least one of a voltagesignal VPTAT and a current signal IPTAT proportional to the localtemperature TL taken from a local spot LS. The analog-to-digitalconverter 64 may convert the output of the temperature detector 62 to adigital signal to determine the local temperature TL represented by nbits.

In some embodiments, the temperature detector 62 may be implemented withfirst and second PMOS transistors M1, M2, a feedback amplifier AMP, aresistor R and first and second bipolar transistors B1, B2, which arecoupled between a power supply voltage VDD and a ground voltage VSS asrepresented in FIG. 13. A voltage dVBE across the resistor R may beobtained as Expression 1

$\begin{matrix}\begin{matrix}{{dVBE} = {{{VBE}\; 1} - {{VBE}\; 2}}} \\{= {{VT^{*}L{n\left( {Ic{1/I}s1} \right)}} - {VT^{*}L{n\left( {n^{*}Ic{2/I}s2} \right)}}}} \\{= {VT^{*}L{n(n)}}}\end{matrix} & \left( {{Expression}\mspace{14mu} 1} \right)\end{matrix}$

In Expression 1, Is1 and Is2 indicate reverse saturation currents of thebipolar transistors B1, B2. Also, Ic1 and Ic2 indicate currents flowingthrough the bipolar transistors B1, B2. Additionally, n is a gain ratioof the bipolar transistors B1, B2, and VT indicates a temperaturevoltage that is proportional to an absolute temperature of thetemperature detector 62. Ln(n) is a constant value and thus the voltagedVBE across the resistor R and the current I2 flowing through theresistor R are proportional to the temperature variation. The voltagesignal VPTAT and the current signal IPTAT may be generated as an outputbased on the voltage dVBE and the current I2 proportional to theoperational temperature.

The on-chip temperature sensor described with reference to FIGS. 12 and13 may be integrated in the same semiconductor die in which a circuitcorresponding to the hot spot is integrated, to be used in a similarmanner as the above-described reference temperature sensor.

FIG. 14 is a diagram representing an example embodiment of a referencetemperature sensor included in the electronic device of FIG. 11.

Referring to FIG. 14, a non-contact temperature sensor 30 may include aninfrared (IR) responsive thermocouple 31. The IR responsive thermocouple31 generates an electromotive force by absorbing the infrared radiantheat emitted from a reference spot RS on the housing case 1020.

Also shown is a voltmeter 32 connected to the thermocouple 31 to measurean electromotive force and a detecting unit 33 which operates inconjunction with the voltmeter 32 to detect the reference temperature TRfrom the measured electromotive force.

The thermocouple 31 may include a pair of first and second metal wirings31 a and 31 b having different physical properties from each other.First end portions of the first and the second metal wirings 31 a and 31b may be coupled to form a joint portion and second end portions of thefirst and the second metal wirings 31 a and 31 b may be connected to thevoltmeter 32, at each side respectively. When the joint portion of thethermocouple 31 is heated by the infrared radiant heat from the externalheat source, an electromotive force may be generated at the jointportion J (not shown) by the Seebeck effect. The electrical currentcaused by the electromotive force generated at the joint portion J maypass through the first and the second metal wirings 31 a and 31 b. Theelectrical potential energy generated by the electrical current may bedetected by the voltmeter 32 that is connected to the second ends of thefirst and the second metal wirings 31 a and 31 b. The joint portion ofthe thermocouple 31 may be positioned at a site relatively close enoughwhere the infrared radiant heat from the reference spot RS maysufficiently reach the joint portion of the thermocouple 31. Forexample, the first and the second metal wirings 31 a and 31 b maycomprise any one material selected from the group consisting of platinum(Pt), iron (Fe), copper (Cu), constantan, or any other suitable materialknown to those of ordinary skill in the art. In the present exampleembodiments, the pair of the first and the second metal wirings 31 a and31 b may include one of a platinum (Pt)-platinum (Pt) pair, an iron(Fe)—constantan pair and a constantan-copper (Cu) pair.

In some embodiments, the non-contact temperature sensor 30 may be spacedapart from the reference spot RS and provide the surface temperature ofthe housing case 1020, that is, the reference temperature TR using theIR radiation heat from the reference spot RS.

According to a DTM operation, a target temperature of the semiconductorchip and/or a target temperature of the housing case may be determinedand set in advance, and performance of a power level of thesemiconductor chip may be restricted automatically if the operationaltemperature of the semiconductor chip exceeds the predetermined targettemperature and/or if the operational temperature of the housing caseexceeds the predetermined target temperature. According to someembodiments, the temperature management of the mobile electronic devicemay be performed efficiently by changing the target temperature of thehousing case based on the temperature of the semiconductor chip.

FIG. 15 is a diagram representing a method of temperature managementaccording to example embodiments.

Referring to FIG. 15, according to example embodiments, the targettemperature TRT may be changed based on the local temperature TL. Forexample, the target temperature TRT may be decreased as the localtemperature Tl increases, as described herein.

In some example embodiments, a power level of an electronic device maybe controlled by comparing the reference temperature TR and the targettemperature TRT to perform the DVFS operation based on the comparisonresult. As described above, the DVFS operation may be performed bycontrolling least one of the operational voltage and the operationalfrequency.

As illustrated in FIG. 15, the power level may be controlled using afirst DVFS operation DVFS1 before time point t1 and after time point t2while the reference temperature TR is lower than the target temperatureTRT, and the power level may be controlled using a second DVFS operationDVFS2 between time points t1 and t2 while the reference temperature TRis higher than the target temperature TRT. In the second DVFS operationDVFS2, the power level may be set lower than that of first DVFSoperation DVFS1 to prevent the local temperature TL from being increasedexcessively.

FIG. 16 is a diagram representing a layout of a temperature managementcircuit in an electronic device according to example embodiments.

Referring to FIG. 16, a temperature management circuit in an electronicdevice 1100 includes a temperature management unit also referred to asand shown as a thermal management unit TMU 100, a reference temperaturesensor (SNR) 200 and a plurality of local temperature sensors SNL1,SNL2, SNL3, 310, 320, 330. FIG. 16 illustrates three local temperaturesensors for convenience of description; however, the number of the localtemperature sensors may vary according to a configuration of theelectronic device 1100 while meeting the operation requirements of agiven electronic device. Other elements in the electronic device 1100are omitted except for the temperature management circuit.

The electronic device 1100 may include a system on chip (SOC) (notshown) and the SOC may include a plurality of subsidiary blocks BLKi, inwhich i=1,2,3,4, which may be individualized by their own functions. Forexample, the subsidiary blocks BLKi may include a core block including acentral processing unit, a memory controller, a display controllerblock, a file system block, a graphic processing unit block, an imagesignal processing block, a multi-format codec block, and any othersuitable block known to those of ordinary skill in the art. Thesesubsidiary blocks may be significant heat sources of the SOC and it maybe necessary to monitor and control the respective temperatures of thesubsidiary blocks BLKi in addition to the overall temperature of theSOC.

The reference temperature sensor 200 may measure a temperature of areference spot RS to provide a reference temperature TR. The localtemperature sensors 310, 320 and 330 may measure temperatures of localspots LS labeled LS1, LS2 and LS3 to provide local temperatures TLlabeled TL1, TL2 and TL3, respectively. The reference spot RS and thelocal spots LS1, LS2 and LS3 may be spaced apart and may be thermallycoupled through media having certain thermal conductivities.

In some embodiments, the temperature management unit 100 may provide atarget temperature TRT and temperature information DTI based on thelocal temperatures TL1, TL2, TL3, TLx and the reference temperature TR.According to some embodiments, the temperature management unit 100 maychange the target temperature TRT corresponding to a limit value of thereference temperature TR based on one or more of the measured localtemperatures TL1, TL2 TL3, . . . TLx. The power level of the electronicdevice 1100 may be controlled based on the temperature information DTIand the target temperature TRT from the temperature management unit 100.

The local spots LS1, LS2, LS3 . . . LSx may correspond to hot spotsadjacent to heat sources or heat aggressors in the electronic device1100 and the local spot LS may be an arbitrary spot that is affected bythe temperatures of the local spots LS1, LS2, LS3, LSx. The referencetemperature TR of the reference spot LS may be lower than a maximumtemperature of the local temperatures TL1, TL2, TL3, TLx.

In some embodiments, a maximum local temperature (TLm) may be determinedamong the plurality of local temperatures TL1, TL2, TL3, TLx asExpression 2.

TLm=MAX{TL1, TL2, TL3, TLx}  (Expression 2)

The target temperature TRT may be changed based on the maximum localtemperature TLm. It may be noted that the higher local temperature hasthe greater influence on the reference temperature, and thus the targettemperature TRT may be changed based on the maximum local temperatureTLm. The method of changing the target temperature TRT based on themaximum local temperature TLm can, in some embodiments, be the same asthe method of changing the target temperature TRT based on the one localtemperature TL as described above.

In other example embodiments, an average local temperature (Tla)corresponding to an average of the plurality of local temperatures TL1,TL2, TL3 . . . TLx may be determined as Expression 3.

TLa=(TL1+TL2+TL3+ . . . +TLx)/x   (Expression 3)

In some embodiments, the target temperature TRT may be changed inresponse to the average local temperature TLa. When a plurality of heatsources affect the reference temperature TR of the reference spot RS,the target temperature TRT may be controlled by considering all of theheat sources in the device.

In still other embodiments, a weighted average local temperature TLwamay be determined such that the weighted average local temperature TLwacorresponds to an average of the plurality of local temperatures TL1,TL2, TL3 . . . TLx multiplied respectively by weight values W1, W2, W3 .. . Wx as Expression 4.

TLwa=(W1*TL1+W2*TL2+W3*TL3+ . . . +Wx*TLx)/x   (Expression 4)

The target temperature TRT may be changed based on the weighted averagelocal temperature TLwa. The influences of the heat sources on thereference temperature TR of the reference spot RS may be represented bythe weight values W1, W2, W3 . . . Wx. In some example embodiments, theweight values W1, W2, W3 . . . Wx may correspond to thermalconductivities between the reference spot RS and the plurality of localspots LS1, LS2, LS3, . . . LSx. The target temperature TRT may becontrolled more precisely by considering influence degrees of the heatsources on the reference temperature TR of the reference spot RS.

FIG. 17 is a diagram representing a mobile device according to exampleembodiments.

Referring to FIG. 17, a mobile device 1200 includes an applicationprocessor (AP) 1210, a connectivity unit 1220, a volatile memory device(VM) 1230, a nonvolatile memory device (NVM) 1240, a user interface1250, and a power supply 1260. In some embodiments, the mobile device1200 may comprise an electronic device such as a mobile phone, a smartphone, a personal digital assistant (PDA), a portable multimedia player(PMP), a digital camera, a music player, a portable game console, anavigation system, or another type of electronic device known to one ofordinary skill in the art.

The application processor 1210 may execute applications such as a webbrowser, a game application, a video player, or any other function auser determines is necessary on their device. The connectivity unit 1220may perform wired or wireless communication with an external electronicdevice. The volatile memory device 1230 may store data processed by theapplication processor 1210 or may operate as a working memory. Thenonvolatile memory device 1240 may store a boot image for booting themobile device 1200. The user interface 1250 may include at least oneinput device, such as a keypad, a touch screen, or any other similarfeature., and at least one output device, such as a speaker, a displaydevice, etc. The power supply 1260 may supply a power supply voltage tothe mobile device 1200.

The application processor 1210 may include a dynamic thermal management(DTM) circuit as described above. The DTM circuit may provide a localtemperature by measuring a temperature of a local spot in the mobiledevice 1200 and provide a reference temperature by measuring atemperature of a reference spot in the electronic device where thereference spot is thermally coupled to the local spot. The DTM circuitmay change a target temperature, also referred to as TRT above,corresponding to a limit value of the reference temperature based on thelocal temperature, and a power level of the electronic device may becontrolled based on the target temperature.

As described above, the method of dynamic thermal management of theelectronic device according to example embodiments may efficientlyperform thermal management of the electronic device by changing thetarget temperature corresponding to a limit value of the referencetemperature based on the local temperature when the local spot and thereference spot are thermally coupled. In some embodiments, the targettemperature may be set to a relatively high value to secure performanceof the electronic device when the local temperature is relatively low.On the other hand, in some embodiments, the target temperature may beset to a relatively low value to achieve operational stability of theelectronic device when the local temperature is relatively high.

The present inventive concepts may be applied to any devices and systemsincluding a memory device requiring temperature management. For example,the present inventive concepts may be applied to systems such as be amobile phone, a smart phone, a personal digital assistant (PDA), aportable multimedia player (PMP), a digital camera, a camcorder,personal computer (PC), a server computer, a workstation, a laptopcomputer, a digital TV, a set-top box, a portable game console, anavigation system, or any other suitable device known to those ofordinary skill in the art

The foregoing is illustrative of example embodiments and is not to beconstrued as limiting thereof. Although a few example embodiments havebeen described, those skilled in the art will readily appreciate thatmany modifications are possible in the example embodiments withoutmaterially departing from the present inventive concept.

What is claimed is:
 1. An electronic device comprising: at least onelocal temperature sensor configured to provide a local temperaturemeasurement by measuring a local temperature of a local spot in theelectronic device, the local spot corresponding to a hot spot adjacentto a heat source of the electronic device; a reference temperaturesensor configured to provide a reference temperature measurement bymeasuring a reference temperature of a reference spot in the electronicdevice, the reference spot being thermally coupled to the local spot; atemperature management unit configured to change a limit value of thereference temperature measurement directly based on the localtemperature measurement; and a processor configured to control a poweroutput of the electronic device based on the limit value of thereference temperature measurement, wherein the temperature managementunit is configured to decrease the limit value of the referencetemperature measurement when the local temperature measurementincreases.
 2. The electronic device of claim 1, wherein the referencespot is affected by the local temperature measurement of the local spot.3. The electronic device of claim 1, wherein the processor is configuredto control the power output of the electronic device by comparing thereference temperature measurement and the limit value of the referencetemperature measurement to perform a dynamic voltage and frequencyscaling (DVFS) operation based on the comparison result.
 4. Theelectronic device of claim 1, wherein the temperature management unit isconfigured to: set a boundary value of the local temperaturemeasurement; and control a change of the limit value of the referencetemperature measurement based on the local temperature measurement andthe boundary value.
 5. The electronic device of claim 4, wherein thetemperature management unit is configured to: compare the localtemperature measurement and the boundary value; maintain the limit valueof the reference temperature measurement to be constant regardless ofthe local temperature measurement when the local temperature measurementis lower than the boundary value; and decrease the limit value of thereference temperature measurement as the local temperature measurementincreases when the local temperature measurement surpasses the boundaryvalue.
 6. The electronic device of claim 4, wherein the temperaturemanagement unit is configured to: compare the local temperaturemeasurement and the boundary value; decrease the limit value of thereference temperature measurement with a first slope as the localtemperature measurement increases when the local temperature measurementis lower than the boundary value; and decrease the limit value of thereference temperature measurement with a second slope of greatermagnitude than the first slope as the local temperature measurementincreases when the local temperature measurement is higher than theboundary value.
 7. The electronic device of claim 1, wherein thetemperature management unit is configured to: set a plurality oftemperature sections of the local temperature measurement; and determinesectional values of the limit value of the reference temperaturemeasurement with respect to the plurality of temperature sections,respectively.
 8. The electronic device of claim 7, wherein the sectionalvalues of the limit value of the reference temperature measurement aredecreased sequentially as the local temperature measurement increases.9. The electronic device of claim 1, wherein the at least one localtemperature sensor comprises: a plurality of temperature sensorsconfigured to provide a plurality of local temperature measurements bymeasuring temperatures of a plurality of local spots, and wherein thetemperature management unit is configured to: adjust the limit value ofthe reference temperature measurement based on the plurality of localtemperature measurements from the plurality of local spots.
 10. Theelectronic device of claim 9, wherein the temperature management unit isconfigured to: determine a maximum local temperature among the pluralityof local temperature measurements; and adjust the limit value of thereference temperature measurement based on the maximum localtemperature.
 11. The electronic device of claim 9, wherein thetemperature management unit is configured to: determine an average localtemperature corresponding to an average of the plurality of localtemperature measurements; and adjust the limit value of the referencetemperature measurement based on the average local temperature.
 12. Theelectronic device of claim 9, wherein the temperature management unit isconfigured to: determine a weighted average local temperaturemeasurement corresponding to an average of the plurality of localtemperature measurements multiplied by weight values; and adjust thelimit value of the reference temperature measurement based on theweighted average local temperature measurements.
 13. The electronicdevice of claim 12, wherein the weight values correspond to thermalconductivities between the reference spot and the plurality of localspots.
 14. The electronic device of claim 1, wherein the processor isconfigured to: compare the reference temperature measurement and thelimit value of the reference temperature measurement to generate acomparison result; and control at least one of an operational voltageand an operational frequency of the electronic device based on thecomparison result.
 15. A method of dynamic thermal management of aportable electronic device comprising: providing a local temperaturemeasurement by measuring a temperature of a hot spot adjacent to a heatsource of the portable electronic device; providing a referencetemperature measurement by measuring a temperature of a housing case ofthe portable electronic device using a sensor on the housing case, thehousing case being thermally coupled to the hot spot; changing a limitvalue of the reference temperature measurement directly based on thelocal temperature measurement; and controlling a power level of theportable electronic device based on the limit value of the referencetemperature measurement, wherein changing the limit value of thereference temperature measurement comprises decreasing the limit valueof the reference temperature measurement when the local temperaturemeasurement increases.
 16. The method of claim 15, wherein changing thelimit value of the reference temperature measurement further comprises:setting a boundary value of the local temperature measurement; andcontrolling a change of the limit value of the reference temperaturemeasurement based on the local temperature measurement and the boundaryvalue.
 17. The method of claim 15, wherein changing the limit value ofthe reference temperature measurement further comprises: setting aplurality of temperature sections of the local temperature measurement;and determining sectional values of the limit value of the referencetemperature measurement with respect to the plurality of temperaturesections, respectively, such that the sectional values of the limitvalue of the reference temperature measurement are decreasedsequentially as the local temperature measurement increases.
 18. Themethod of claim 15, wherein providing the local temperature measurementfurther comprises: providing a plurality of local temperaturemeasurements by measuring temperatures of a plurality of hot spots, andwherein changing the limit value of the reference temperaturemeasurement further comprises: changing the limit value of the referencetemperature measurement based on the plurality of local temperaturemeasurements.
 19. A temperature management circuit of an electronicdevice, comprising: a local temperature sensor configured to provide alocal temperature measurement by measuring a temperature of a local spotin the electronic device, wherein the local temperature sensor is as anon-chip temperature sensor that is integrated in a semiconductor die inwhich a circuit corresponding to a heat source of the electronic deviceis integrated and wherein the local spot corresponds to a hot spotadjacent to the heat source of the electronic device; a referencetemperature sensor configured to provide a reference temperaturemeasurement by measuring a temperature of a reference spot in theelectronic device, the reference spot being thermally coupled to thelocal spot; and a temperature management unit configured to change alimit value of the reference temperature measurement directly based onthe local temperature measurement, wherein the temperature managementunit is configured to decrease the limit value of the referencetemperature measurement when the local temperature measurementincreases.
 20. The temperature management circuit of claim 19, whereinthe reference temperature sensor is implemented as a non-contacttemperature sensor.